Continuously electrolyzing alkali chlorids.



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GONTINUOUSLY EvLECTRDLIZING ALKALI CHLORIDS.

(Application led Nov. 17, 1900.)

UNTTn STnTns PATE T Tirion.

VILIIELM GINTL, OF AUSSEGG, AUSTRIA-HUNGARY.`

CONTlblUOUSLY ELECTROLYZING ALKALI CHLORIDS.

SPECIFICATION forming part of Letters Patent No. 690,141, dated December 31, 1901.

Application led November 17,1900. Serial No. 36,855. (No specimens.)

To @ZZ whom t may concern:

Be it known that I, WILHELM GIN'rL, of Aussegg-on-the-Elbe, Bohemia,Austria-Hun gary, have invented certain new and useful Improvements in the Art of Continuously Electrolyzing Alkali Chlorids and the Like, of which the following is a specification, accompanied by drawings that illustrate one form of apparatus for carrying out the improved art or process.

The object of the invention is to utilize the current to as nearly the theoretical limit as possible and to produce cheaply and efficiently strongly alkaline cathode liquors.

The several novel features of the process and combinations of features are pointed out in the following description and claims. In the broader aspect of the invention some of these features of the process may be used without the others.

One way in which sodium chlorid has been electrolyzed employs separate chambers for the anodes and cathodes and a mercury seal connecting the chambers or cells electrically, but hermetically separating them hydraulically from each other. Another way has been to utilize the specific gravities of the different solutions to keep separate the anode liquor and the cathode liquors and maintain them on two sides of a separating vertical wall or diaphragm ,which extends down into the bath, but leaves free liquid communication and free electrolytic communication beneath the diaphragm. The present improvement relates particularly to this latter type of processes, and it seeks, among its other objects, to overcome the trouble that has arisen by the disturbance caused by the inflow of the fresh electrolytic solutions.

In the preferred way of carrying out the present improved process the fresh electrolyte is not delivered into the cell and permitted to flow freely downward, but, on the contrary, is delivered gently and widely distributed upon the anode, and its downflow from the anode is carefully restricted, so as to counteract itstendency to flow down and disturb the stratification and so as to also cause the electrolyte to meet the rising bubbles of chlorin gas and be thereby intimately mixed. A constant liquid-level in the bath is maintained by allowing the bath to overflow from the cathode-compartment. erating under proper conditions for the separation of sodium chlorid, there will be at the bottom of the bath a strong solution of caustic soda, and this will entend up into the cathodecompartment; but in the anode-compartment, around and especially above the anode, there is the fresh inflowing electrolyte, while beneath the anode the liquid diminishes progressively downward in the quantity of sodium chlorid contained and increases in the quantity of caustic soda contained. These conditions are reached and maintained with little, if any, disturbance, owing to the restricted downpourin g of the fresh electrolyte.

In this process, op

"While very many forms of apparatus may be devised to carry ont this process, the form shown in the accompanying drawings is very much preferred. This forms the subject-matter of the copending application, Serial No. 32,598, filed October 10, 1900.

` Having already described the processbriey and generally in the abstract, it will now be explained more in detail and illustrated by its use in connection with the special form of apparatus shown in the accompanying drawings.

Figures l, 2, 3, and et are respectively a vertical central longitudinal section, a transverse central section, a side elevation, and a plan View of an individual bell. Figs. 5, 6, and 7 are a vertical section through the vat, showing the rest of the apparatus in full, a vertical section of the same corresponding to Fig. l, and a plan view of a complete bath apparatus. The section planes marked 5 5 6 6, tc., on the drawings show the planes upon which the sections shown in correspondinglynumbered figures are taken.

Each bell preferably consists of an inverted sheet-iron box e, narrow in proportion to its length, open at the bottom and closed above and coated inside with a layer of non-conducting refractory material-such, for example, as glass or eai'thenwarewhich should be impervious to the liquors. This layer or lining extends somewhat beneath thelower edge of the box e. The anode is a carbon bar or rod dof a size that leaves but a smallinterval between its sides and ends and the walls of the bell-for example, a few millimeters. The anode is preferably of carbon provided with IOO an integral carbon upright b, sealed in an aperture in the bell and coated with insulating material, such as paraffin, to prevent any formation of chlorin on its surface. The currentis supplied through this upright b. This vertical carbon b is provided with a central perforation c and two lateral distributingpipes al, through which the fresh electrolytic liquor enters. The upper surfaces of thepipes d are perforated to insure an equal and gentle distribution of the liquor. Each box e may itself serve as far as itdips into the liquid for a cathode. Openings g or f in the top of each bell permit the eduction of the chlorin gas generated. As shown in Fig. 7, only one bell of each bath needs to be provided with an opening f for leading the chlorin to its ultimate destination if the openings g of the several cells are so connected that the chlorin may pass freely from bell to bell. As shown in Figs. 5, G, and 7, many of these bells or cells are placed in a single vat or tank h, made of insulating refractory material'or coated with such. Glass or slate may, for example, be used. Care should be taken to leave both underneath and on the sides of the several bells su fcient space for the col'- lection and flow of the alkaline lye. The outlet or overflow pipe for all the bells belonging to the same bath is placed at a su fficient height to maintain the level of the anode liquor,which is in direct communication with the outer lye, several centimeters above the pipes that distribute the fresh electrolyte. By admitting the fresh solution above the anode and gently and equally distributing it, thereby forcing it to pass through the narrow intervals or spaces around the anodes, continually meeting the rising chlorin bubbles, it is intimately mixed with the anode liquor. In this way a constant uniform composition of the liquid at the anodes is attained, and it can not grow so weak by the free downiiow of the fresh solution as to lead to the electrolysis of water. As there is a'considerable interval or space as measured vertically between the bottom of each anode and the lower edge of the bell, the

chlorinated anode liquor liesy above but not in immediate contact with the strong alkaline cathode lye. In this space within each bell the conditions are produced for the formation Vof Strata of continually decreasing alkalinityv and specific weight from the bottom upward to the anode. Thus it will be seen that the chlorinated anode liquor,which extends somewhat below the anode, is in contact with a layer extremely poor in free alkali. If the fresh brine or electrolyte be introduced at a rate corresponding to that at which the current decomposes and separates it, the apparatus will then operate under the following conditions: The fresh electrolyte will lie above and around the anode and through it will pass the ascending chlorin gas. It will iow gently down through the restricted spaces around the anodes at the same rate at which it is decomposed, so that when the normal conditions are established there 4will be no accumulation of salt or of chlorin gas in the space below the anodes and, on the other hand,no accumulation of the alkaline hydrate in the vicinity of the anodes. The alkaline liquor will be drawn off as it is formed and the passage or the migration of the alkali ions to the cathodes will be just equal to the rate at which salt is electrolyzed. These conditions are maintained uniformly, the alkalinity of the liquor increasing continuously downward beneath the anodes and the fresh supply of electrolyte not being allowed to' pour freely down beneath the anodes and so disturb or destroy the stratification. The anodes might also be made of perforated material to effect the restrictive vaction of the electrolyte, as shown in Fig. l, and afford only by these perforations alone a sufficient passage-way for the electrolyte.

As it isl evident that the above-described process is applicable for the electrolysis of other salts, such as uorids and some car- .which consists in passing a current'from anode to cathode through the electrolyte gently introducing the fresh electrolytic solution in the immediate vicinity of the anode,- and in a chamber or compartment separate from the cathode, and drawing olf the liquid from the immediate vvicinity of the cathode thereby producing a gradual movement of liquid to= ward the cathode, and in restricting the downiiow of the electrolyte in the vicinity of the anode, and causing it to meet the rising bubbles of gas and be intimately mixed thereby; whereby the rapid downpour and dissemination of the electrolyte in the lower portions of the` bath are prevented vand a substantially constant stratification is maintained substantially undisturbed.

2. The improvement in the process forlthe continuous electrolysis of gas-producing salt,- which consists in passing a current from an-l ode to cathode through the electrolyte, gently introducing the fresh electrolytic solution into l a space or chamber above the anode, main-l taining the level of the solution substantially above the anode, and restricting its downiiow around the anode, and forcing it to meet the rising bubbles of gas and be intimately mixed thereby, and in drawing ci the liquid from beneath the said anode to a separate chamber containing the cathode; whereby a stratification of the solutions is produced and maintained, the solution above the anode being richest in the electrolyte to be decomposed, substantially'as set forth.

3. The improvement in the process for the continuous electrolysis of common salt,which consists in passing a current from anode to cathode, gently introducing the fresh electrolytic solution in the immediate Vicinity of the anode, and in a chamber or compartment separate from the cathode, and drawing off the liquid from the immediate vicinity of the cathode, at a level above the highest level of communication between the said chamber or compartment and the vicinity of the cathode, thereby producing a gradual movement of liquid toward the cathode, and in restricting the down flow of the electrolyte in the vicinity 

